1. Technical Field
The present invention relates to a light source module, and more particularly, to a light source module, a light source assembly having the light source module and a display device having the light source module.
2. Discussion of the Related Art
A display device typically includes a backlight assembly providing light to a display panel so that an image may be displayed even when the amount of ambient light would be insufficient to illuminate the display panel. Examples of a light sources employed in the backlight assembly include a cold cathode fluorescent lamp (CCFL) or a lighting unit including one or more light-emitting diodes (LEDs).
Conventionally, a hold-type backlight assembly has been used. In the hold-type backlight assembly, light is generated when power is applied to the backlight assembly without regard to the displayed image. However, a dimming-type backlight assembly has recently been introduced. In the dimming-type backlight assembly, luminance of the backlight is controlled in accordance with the desired luminance of the presently displayed image so that when a darker image is being displayed, the backlight may be dimmed accordingly. This dimming of the backlight allows for a reduced power consumption and increased contrast ratio.
There are three approaches for controlling luminance in a dimming-type backlight assembly. These approaches may be characterized as 0-dimensional dimming (0-D), 1-dimensional dimming (1-D), and 2-dimensional dimming (2-D).
In 0-D dimming, only the total luminance of the backlight may be controlled and the backlight is delivered substantially evenly across the entire display panel. In the 1-D method, the backlight is divided into a set of predetermined lines, and luminance is controlled separately for each of the predetermined lines. In the 2-D method, also known as local dimming, the backlight is divided into predetermined areas, and the luminance of each area is controlled. Under this approach, the quantity of light supplied to each pixel or group of pixels of the display device may be separately controlled. In a 3-dimensional dimming (3-D) method, also known as color dimming, not only can the quantity of light supplied to each area be changed in accordance with the image being displayed, but the color of that light can be changed as well. For example, the quantity and color of light supplied to each pixel or group of pixels of the display device may be separately controlled.
Unlike a CCFL, an LED is substantially a point light source. For this reason, and other physical properties of LEDs, LED backlights may provide for low power consumption and dimming that may be driven using a variety of methods. However, LEDs may be vulnerable to heat. Accordingly, when an operating temperature of an LED exceeds a limit value when driving a point light source, the lighting efficiency of the point light source may rapidly decrease, and the usable lifespan of the point light source may be shortened. Thus, when point light sources serve as a light source of a backlight assembly, heat generated from the point light sources must be properly dissipated.
In addition, LED-based 2-D and 3-D dimming-type backlight assemblies may be relatively expensive to manufacture costs in comparison with a backlight assembly including a fluorescent lamp. Also, as the number of point light sources employed in a backlight assembly increases, the amount of heat generated from the backlight assembly and a display device having the backlight assembly also increases, thereby reducing the usable lifespan of the point light sources and the backlight assembly, decreasing efficiency, and greatly increasing manufacturing costs.